多种颜色节点
#footer {
 
  background: -webkit-linear-gradient(left,red,orange,yellow,green,blue,indigo,violet) !important;
 
  background: -o-linear-gradient(left,red,orange,yellow,green,blue,indigo,violet) !important;
 
  background: -moz-linear-gradient(left,red,orange,yellow,green,blue,indigo,violet) !important;
 
  background: linear-gradient(to right, red,orange,yellow,green,blue,indigo,violet) !important; 
}
